Wye not give this a go?
Something very special is on offer on Sunday July 16 with the Wye Valley Tunnel Run offering a run through a disused railway tunnel, over 1km long.
Races are staged in 6km, 10km, half marathon and full marathon lengths, with all running out and back through the tunnel.
All routes make use of a former railway line, which means almost completely flat terrain and some very pleasing tree cover, with longer routes adding some attractive riverside paths.
The half marathon and marathon routes turn around at the Old Station, Tintern, a converted Victorian building within a beguiling ten-acre spot beside the River Wye.